Back in the 1980s, Dr. Melanie Dreher and a team of researchers conducted one of the most in-depth longitudinal studies on the use of marijuana during pregnancy that has ever been published. But, chances are, you haven’t heard about it.

The studies

Dr. Dreher and her team compared babies of Jamaican women who smoked marijuana during pregnancy and those who did not. The researchers tested infants on a variety of functions one, three, and 30 days after birth. Their findings were surprising: cannabis-exposed babies scored significantly higher in their reflex tests as well as tests of basic functions like blood pressure and heart rate. The infants of cannabis-using moms were also less irritable and more alert.

Dreher’s team then followed up with the children at ages four and five. The follow-up study used the McCarthy Scales of Children’s Abilities to test IQ and behavioral performances. It also took home environment, and school attendance into account. The team found no difference between children in the two groups. Dr. Dreher explains:

We can’t really conclude that there’s necessarily no impact from ganja use prenatally whatsoever, but what can be concluded is that the child who attends basic school regularly, is provided with a variety of stimulating experiences at home, who is encouraged to show mature behavior, has a profoundly better chance of performing at a higher level on the skills measured by the McCarthy whether or not his or her mother consumed ganja during pregnancy.

Biased publishing

There was one major problem with Dr. Dreher’s studies, however. The results didn’t say the right things. Dreher’s research was originally funded by the National Institute on Drug Abuse (NIDA), but after the results of the five-year study showed no statistical difference between the two studied groups, NIDA took away her funding.

Instead, NIDA suggested that she continue her research under the supervision of approved scholar, Peter Fried, who’s previous work had found that marijuana harms fetal development. In the 24 years since Dr. Dreher’s work was first published, the two studies have been cited just over 100 times via Google Scholar. Fried’s collective works have been cited well over 700. Though, both collections of research were in-depth longitudinal studies.

Discussing the bias toward publishing negative facts about marijuana use, Dreher says: “I think we have a lot of red herrings […] you know, a red herring is something that distracts us from more important questions.”

Dr. Dreher gives an amazing speech about her work in the video below. She not only describes her work but gives insightful commentary on how we value research conducted among different cultures. Definitely worth a watch!

Do you feel that there is a bias toward publishing negative research on cannabis use? How do you feel about Dr. Dreher’s speech? Share your thoughts with us on social media or in the comments section below. We’d love to hear from you!